Design and assessment of two broad-spectrum multi-epitope vaccine candidates against bovine viral diarrhea virus based on reverse vaccinology

Bovine viral diarrhea virus (BVDV) is a significant pathogen that exerts substantial economic influence on the global cattle industry. Developing a safe and effective novel vaccine targeting various BVDV subtypes is critical for controlling BVDV infection. In the study, we created two distinct multi-epitope vaccines by linking highly conserved and dominant cytotoxic T-lymphocytes (CTL), helper T-lymphocytes (HTL), and B-cell epitopes from either the E0 or E2 envelope glycoprotein of diverse BVDV subtypes. To enhance immunogenicity, β-defensin-3 was fused to the N-terminus of these constructs as an adjuvant. Using multiple immunoinformatics tools, we conducted an analysis and assessment of the vaccine constructs' physicochemical properties and immunological features. Consequently, two prospective vaccine candidates named BVDV-M1 and BVDV-M2 were successfully designed and shown to be stable, antigenic, non-allergenic, and non-toxic. The optimized vaccine 3D models exhibit excellent structural quality. Molecular docking revealed a strong interaction between the vaccines with bovine TLR2 and TLR4. The stability of the docked vaccine-TLR complexes was confirmed through molecular dynamics simulation. Immune simulation analyses indicated that both vaccines have the potential to induce high levels of antibodies IgM, IgG and the cytokines IFN-γ and IL-2. Furthermore, the vaccine's efficient expression in the E.coli system was secured through codon optimization coupled with in silico cloning. Summarily, the designed multi-epitope vaccines have the potential to elicit robust humoral and cellular immune responses, positioning them as hopeful broad-spectrum vaccine candidates against the currently prevalent BVDV subtypes.